基于rGO/BB水凝胶粒子电极的三维电化学吸附碳酸铀酰离子研究

Three-dimensional electrochemical adsorption of uranyl carbonate ions based on rGO/BB hydrogel particle electrodes

铀的采冶过程中,会产生大量的含铀废水,容易造成地下水的污染。在受污染的地下水中,铀常与碳酸盐结合形成扩散性更强、迁移性更高的碳酸铀酰络合物,这使得铀的去除变得更加困难。将氧化石墨烯和竹炭共混,通过低温水热还原反应将竹炭组装至还原氧化石墨烯水凝胶的骨架上,制备具有三维多孔结构的rGO/BB水凝胶。将rGO/BB水凝胶作为三维电化学系统中的粒子电极,探究电解质(硝酸钠)浓度、外加电压、极板间距、pH和rGO/BB水凝胶粒子电极用量等因素对三维电化学系统吸附碳酸铀酰离子性能的影响。实验结果表明,在pH4~8、极板间距4cm、电压5 V、rGO/BB水凝胶用量90mg的条件下,对200mL浓度为1~1000 mg·L^(-1)的碳酸铀酰均具有良好的吸附率,即使当碳酸铀酰浓度为1000 mg·L^(-1)时,14 h吸附率依然可以达到87.56%。经过5次吸附解吸循环后,吸附率仍然保持在87%以上,具有较好的循环再生性能。引入和使用rGO/BB水凝胶粒子电极显著提高了电化学系统对铀的吸附能力,其中羧基和羟基对铀吸附发挥着重要作用。这些结果说明,基于rGO/BB水凝胶粒子电极的三维电化学系统对去除碳酸铀酰离子具有很大的应用潜力。

[Background]In uranium mining and smelting,a significant amount of uranium-containing wastewater is generated,which can easily cause groundwater pollution.In polluted groundwater,uranium often combines with carbonates to form more diffusive and migratory uranyl carbonate complexes,making uranium removal more difficult.[Purpose]This study aims to consider the performance of a three-dimensional electrochemical system of rGO/BB hydrogel particle electrodes on uranyl carbonate,and implement an efficient method for removing uraniumcontaining solutions.[Methods]Firstly,graphene oxide(go)samples were prepared by modified Hummers method,then,the effects of electrolyte(sodium nitrate)concentration,applied voltage,electrode spacing,pH value,particle electrode dosage,and initial uranium concentration on the adsorption performance of uranyl carbonate ions by a three-dimensional electrochemical system were investigated,and the recycling performance of the system was studied.Finally,the adsorption mechanism of uranium was analyzed by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),Raman spectroscopy,and X-ray photoelectron spectroscopy(XPS).[Results]Experimental results show that under the conditions of pH value of 4~8,electrode spacing of 4 cm,voltage of 5 V,and rGO/BB hydrogel dosage of 90 mg,200 mL of uranyl carbonate with a concentration of 1~1000 mg∙L^(−1)exhibits good adsorption efficiency.Even when the uranyl carbonate concentration is 1000 mg∙L^(−1),the adsorption rate can reach 87.56%in 14 h.After five cycles of adsorption and desorption,the adsorption rate remains above 87%,thus showing good recycling performance.The addition and use of rGO/BB hydrogel particle electrodes significantly improves the adsorption capacity of the electrochemical system for uranium,in which carboxyl and hydroxyl groups play a major role in uranium adsorption.[Conclusions]The results of this study show that the three-dimensional electrochemical system based on rGO/BB hydrogel particle electrodes has great application potential for removing uranyl carbonate ions.